It has been known for a very long time to design a nacelle for an aircraft adapted to be mounted around an engine including a blower casing, said nacelle comprising a connecting structure adapted to be mounted on the downstream edge of said casing, on the one hand, and on a pylon, on the other hand, this pylon being fastened to a wing or part of the fuselage of the aircraft.
An engine change is effected by disconnecting the engine at the level of the suspension. Some cowls of the nacelle, known as the Transcowl and the Fan Cowl, remain connected to the pylon and must therefore be held open to enable replacement of the engine. A device for raising and lowering the engine is then used. This device comprises two independent longitudinal members disposed transversely relative to the axis of the engine, one being fixed to the front of the pylon and the other to the middle. A bootstrap type lifting system is provided at each end of the two longitudinal members so as to be able to adjust the height of the engine at four points, each lifting system being independent of the other three.
However, employing a one-piece propulsion unit instead of a standard assembly as referred to above has recently been envisaged. Accordingly, in such a one-piece propulsion unit, the engine, the nacelle and the pylon are inseparable and the usual interface disappears.
In such a configuration, the standard engine change maintenance procedure is rendered obsolete since the pylon is now fastened to the engine and the nacelle and thus can no longer support the two longitudinal members described above.